#include<stdio.h>
#include<unistd.h>
int main(){
    int pid;pid = fork();
    switch(pid){
        case -1:
            printf("Error in fork()\n");
            exit(1);
        case 0:
            execl("/bin/ls","ls","-l","-color",NULL);
            printf("execl fail!\n");
            exit(1);
        default:
            wait(NULL);
            printf("is completed!\n");
            exit(0);
    }
}